Upload
others
View
5
Download
0
Embed Size (px)
Citation preview
Impacts on ocean biology I: physiological underpinnings, projections and uncertainties
CLIMATE CHANGE
Hans-O. Pörtner: AR5 CLA WGII CH. 6, Ocean Systems, Ocean products in TS and SPM, CC-Boxes, SYR, SEDAR6 Co-chair WGII
UNFCCC Art. 2: ......prevent dangerous anthropogenic interference.... ............allow ecosystems to adapt naturally... ............ensure that food production is not threatened... ............enable economic development to proceed in a
sustainable manner
A role for natural systems to define the long-term global (climate) goals (LTGG, relative to preindustrial)?:
Projection of impacts:Define the key risks
Identify avoided impacts
Article 2 UNFCCC
Historical change in SST
RCP 2.6
RCP 8.5
projected
... warmingAccording to emission scenarios oceans are:
CMIP5 model runs
Gattuso et al., 2015
WGI Figure 6.30
... losing oxygen
Historical projected
committedclimate change
Historical Projections...acidifying
committed
Climate change in the oceans: warming, acidification, expanding hypoxia
occur on top of regional and natural variability: Organism and ecosystem functional changes may depend on climate zone
warmingon top of
means and variability
Pörtner et al. 2014
Pelejero et al. 2010
Natural variabilityin pH
Ocean surface layer
Deep ocean
Natural variability: vertical distribution of PCO2, pH
RCP2.6pH change = −0.13“What we hope for”
RCP8.5pH change = −0.42“Where we’re headed”
Average pH of the ocean surface
pH
Year
The ocean is acidifying rapidly
Figure courtesy of Jim Orr
We are here
WGI 3-18
Observations in surface waters
Historical Projections
Oceans are acidifying
+0.8°C to >>2 °C
How to explain ocean acidification?The earth has seen much higher atmospheric CO2 levels… but actual rates of CO2 accumulation are exceptionally high.
TodayGlacial-Interglacial
Currently, atmospheric CO2 levels change 100-fold faster than in glacial- interglacial intervals.
Calculated from Petit et al (1999) Calculated from Keeling and Whorf (2005)
Courtesy: Ken Caldeira
The uptake of excess CO2 from Ocean and atmosphere by weathering occurs in > 10,000 years.
Volcanic CO2 release =
CO2 removal by weathering
≈ 0.1 PgC / yr
CO2 emissions by human activities ≈ 7 PgC / yr
Pg = Petagram (1015 grams)
Human activities exceed by far the capacity of natural processes (sediment weathering) for buffering
www.globalchange.umich.edu
Natural volcanicCO2 emissions
More than 50 timesnatural CO2 emissions
Natural CO2 cycleCO2 from coal,
oil and gas
Bill
ions
of t
ons
carb
on p
er
year
CO2fromcoal,oil,andgas
Weathering: CO2 neutralisation occurs onTime scales >10 000 years
Caldeira and Wickett, 2003, 2005
Pre-industrial
Today
∆pH = - 0.12
32 % more acidification
2100
∆pH = - 0.45
2.8 fold more ….
2300
∆pH = - 0.77
5.9 fold more …
Specific effect of CO2: Reduction of carbonate levels in the oceans
Verons 2009
WAragonite =Ca 2+[ ] CO3
2-[ ]Ksp,Aragonite
*
Calcifiers need over-saturation and prosper at W > 3.3 (coral reefs)
Feely et al (in press) with modeled saturation levels from Orr et al (2005)
Calcium carbonate (aragonite) saturation levels 1765 - 2100
Observations: Oxygen depletionAreas with low oxygen expand:
deadzones at the coastOxygen minimum level reached in the water column
Habitat-“comprimation” und –loss for pelagic fish
Gruber (2012)
.....Extension, shoaling of hypoxic / anoxic dead zones.....
.....associated with enhanced CO2 accumulation
L. Stramma et al., Science 320, 655 -658 (2008)
(A) Eastern tropical North Atlantic
(10° to 14°N, 20° to 30°W)
dissolved oxygen
(µmol kg-1)
depth(m)
(D) Eastern equatorial Pacific Ocean
(5°S to 5°N, 105° to 115°W)
Climate change in the oceans: warming, acidification, expanding hypoxia
occur on top of regional and natural variability: Organism and ecosystem functional changes may depend on climate zone
light, nutrients, food
warmingon top of
means and variability
Pörtner et al. 2014
true also for:
progressive acidification
(Pelejero et al., 2010)
expanding oxygen minimum zones
(Stramma et al., 2008)
Ecosystem effects of ocean warming, acidification, hypoxia?
Are there unifying principles involved?
Bent
hic A
lgae
Bent
hic C
nidar
ians
Bent
hic M
ollus
ks
Bent
hic C
rusta
cean
Bent
hic In
vert
(Oth
er)
Phytop
lankton
Zoop
lankton
Larv
al Bo
ny Fi
shes
Non-B
ony F
ishes
Bony
Fish
es
All Tax
a
DIS
TRIB
UTI
ON
CH
AN
GE
(Km
per
Dec
ade)
-20
0
20
400
Standard Error
Mean
Standard Error
(359)100
World-wide marine species displacements due to climate change
OBSERVATIONS
WGII, SPM.2
+0.8°CGMT
Cod
Anglerfish
Snake blenny
Perry A.L. et al., 2005
Snake blenny (Lumpenus lampretaeformis)
Anglerfish(Lophius piscatorius)
Cod(Gadus morhua)
Data : 1977 - 2001
East Atlantic species are moving North …..to various degrees (!)
Shifting biogeographies~ Different thermal
sensitivities→ Changes in community
composition
Knowing the physiological underpinnings:
How to identify cause and effect and explain these observations?
Why?Such knowlege enhances confidence in projections of the
impacts of different climate futures!
PROJECTING VARIOUS FUTURES (PRESENT CHOICES)Poleward Shifts in ocean phytoplankton and
primary production...and a small overall decrease
IPCC AR5 WGII Figure 6.13
4°C~1.5°C
+1.5 to>>2 °C ... warming:
Considering ocean currents and stratification
CHANGE IN MAXIMUM CATCH POTENTIAL (2051-2060 COMPARED TO 2001-2010, SRES A1B, 2°C warming of global surface T0.7°C warmer Sea Surface T)
<50% -21 – 50%
-6 – 20% -1 – 5% No data 0 – 4% 5 – 19% 20 – 49% 50 – 100% >100%
WGII, 6-14, SPM.6, SYR 2.6
2051-60: shifted productivity, fish and invertebrate biodiversity
... Warming, a simplified view into the future: +2°C
HIGH RISK FOR FISHERIES AT LOW LATITUDES:small human adaptation capacity over time
CHANGE IN MAXIMUM CATCH POTENTIAL (2051-2060 COMPARED TO 2001-2010, SRES A1B, 2°C warming of global surface T0.7°C warmer Sea Surface T)
<50% -21 – 50%
-6 – 20% -1 – 5% No data 0 – 4% 5 – 19% 20 – 49% 50 – 100% >100%
WGII, 6-14, SPM.6, SYR 2.6
2051-60: displaced and reduced fish and invertebrate biodiversity... warming: Food security constrained, ....Fisheries
..... 2°C:Combined human pressures
affecting presently overexploited stocks.
BACKGROUND: OVERFISHING caused
predatory fish biomass to decline
(by ≈ 70%!)
Christensen et al.MEPS 512: 155–166, 2014
+2°C
Latitude of Field Population (°N or S)0 10 20 30 40 50 60 70 80 90
Wat
er Te
mpe
ratu
re (°
C)
-5
0
5
10
15
20
25
30
35
40
45
50
(3 spp)
(3 spp)
Pörtner and Peck 2010.
Metaanalysis: Across latitudes lethal limits and preferred temperatures reflect thermal specialization on climate and the limits of
the thermal niche
large juveniles and adults of various fish species
Thermal windows (niches): Large scale patterns with respect to temperature
Peck to al. 2009,
updated for Pörtner et al.
2010
Upper temperature limits and rate of change in Antarctic ectotherms
Rate of change
Upper temperature limit (°C)
0
2
4
6
8
10
12
14
16
18
20
day-1 week-1 1 month 3 month
Functional meaning?
(in experiments)
0Exposure time at T > Tp
Lethal temperature
upper Tp
0
Tem
pera
ture
(°C
)
Tp
Heat excess tolerated over time ((T–Tp) * h)
Pörtner, 2010
A heat tolerance budget delaying mortality: underlying mechanisms?
-2,0
-1,0
0,0
1,0
2,0
3,0
-3,0
-2,0
-1,0
0,0
1,0
2,0
3,0
-3,0 -2,0 -1,0 0,0 1,0 2,0 3,0
Barents Sea
North Sea
Temperature anomaly
Cod
recr
uitm
ent a
nom
aly
-2,0
-1,0
0,0
1,0
2,0
3,0
-3,0
-2,0
-1,0
0,0
1,0
2,0
3,0
1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995
Barents SeaSpring water temperatureCod recruitment
North SeaWinter water temperatureCod recruitment
Ano
mal
y
Colosimo et al. 2003, Pörtner at al. 2008
Temperature dependent recruitment success in cod
La Sapienza
Unicellular Eukaryotes(Fungi, Protozoans)
Prokaryotes
Metazoa
Organisms (groups)
Organisationalcomplexity
Functional units
Adding higherlevels of
function andcoordination
Plants
Status
productive
productive
productive
productive
productive
Maximum heattolerance (˚C)
> 90
55-60
ca. 42
ca. 42
ca. 41
Pörtner (2002)
...when explaining thermal limits & windows: where to look across organisms?
Unicellular Algae
Highest complexitylevels
Compartmental coordination
Membrane functionsMolecular functionsMetabolic complexes
multiple organelles
The
evol
utio
nary
bac
kgro
und
Meta-analysis of the literature on thermal specialization:
Maximum heat limits (sublethal, loss of productivity)
across marine organism domains
related to habitat
D. Storch et al. Global Change Biology 2014
The
evol
utio
nary
bac
kgro
und
Meta-analysis: Thermal window widths (sublethal) across marine organism domains
D. Storch et al. Global Change Biology 2014
D. Storch et al. Global Change Biology 2014
Meta-analysis: Thermal limits found at the highest level of organismal complexity
The evolutionary background / brickwall
Higher (complex) organisms will become extinct in the warmest ocean areas.
Such projections relate to observed distribution patterns during warming periods in earth history.
Organisms respond to shifts in nutrients (ocean currents) as well as changes in temperature (causing stratification), CO2 accumulation, hypoxia.
Physiological underpinnings?:
How to explain observations across organism domains?
....as a basis and support for projections
End of Part I
Thank you!